(a) Field of the Invention
The present invention relates to a decoding method and a receiver using the decoding method. More particularly, the present invention relates to a method for decoding a signal and a receiver using the method when a transmitter transmits the signal by using a plurality of antennas in an Alamouti space-time encoding scheme, in a multiple input multiple output (MIMO) system for transmitting/receiving the signal by using a plurality of antennas.
(b) Description of the Related Art
Recently, requirements of various communication services have increased, since information and communication services have been popularized and high quality multimedia services have been introduced. Accordingly, it is required to increase capacity of communication systems, and more specifically, of wireless communication systems rather than wired communication systems.
Basically, available frequency resources must be shared since they are limited in the wireless communication environment. To increase the capacity in communication systems in the wireless communication environment, a method for finding available frequency bandwidths and a method for increasing efficiency of given resources are used. Among those methods, a space-time coding method for increasing radio resource efficiency has been actively studied, in which reliability of communication links is increased by a diversity gain without increasing bandwidth since a plurality of antennas are provided to a transmitter and a receiver to obtain additional space for resource application, and a data rate is increased by performing parallel transmission in a spatial multiplexing method.
A space-time block encoding method suggested by Alamouti in a publication entitled “A simple transmit diversity technique for wireless communications” IEEE J SAC, vol. 16, no. 8, in October 1998, is a representative transmission diversity method for preventing radio channel fading by using a plurality of antennas in a transmitter and a receiver. In the above method, two transmitting antennas are used to receive a maximized diversity gain, in which a diversity order is a product of the number of transmitting antennas and the number of receiving antennas.
In addition to the space-time block encoding method, a decoding method thereof has also been suggested in the above method by Alamouti. The suggested decoding method is to obtain maximum performance of a maximum likelihood decoding method. While a transmitter concurrently transmits two symbols, it is not necessary to concurrently decode the two symbols since the two symbols are separately decoded in the decoding method. However, every constellation point of each symbol has to be searched in a process for decoding the respective symbols. Therefore, there is a problem in that complexity in realizing a decoder for searching the constellation point is increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.